1. Field of the Invention
The present invention relates to systems that provide signals that occur in an assigned time slot of a multi-time slot repetitive frame, the assigned time slot being determined by input data and, more particularly, to a circuit for reducing the chance of an error in the data from causing the signal to be provided in an incorrect time slot.
2. Description of the Prior Art
In many situations where pulse code modulation (PCM) is used in conjunction with time division multiplexing (TDM), a signal is provided in an assigned time slot of a multi-time slot repetitive frame, with the assignment of the time slot being determined by input data. Errors occurring in the input data could result in the signal being provided in an erroneous time slot. Errors in transmitted data are often intermittent perturbations or spurious signals which are only of a short duration and quickly disappear. However, such data errors could result in significant system failure by the signal being provided in a wrong time slot.
There are frequently situations where timing strobes are generated in an assigned time slot, and the strobes may be transmitted over a bus that may be subject to interference. Such interference could cause a strobe to be temporarily lost or could cause extra strobes. In either event, the system responsive to the strobe would be adversely affected.
In most cases, the signals are generated in response to a strobe, the timing of which is determined by the input data. Thus, the problem can be distilled down to a situation where a strobe is to be repeatedly generated in the same time slot of a frame with the time slot changing only occasionally in response to changed input data; however, disturbances can result in the temporary generation of strobes in improper time slots. The prior art did not provide a way to reduce the chance of the disturbances causing strobes to be provided in the wrong time slot.